Many types of radiation detectors include a set of superimposed semiconductor layers, comprising an absorbent layer, the energy gap of which is adapted so that the absorbent layer absorbs a radiation, thus generating an electron-hole pair. The band structure of such detectors is provided so that the electron and the hole thus generated are separated from one another and an electric current therefore appears when the radiation is absorbed. A radiation detector of the aforementioned type is for example known from document FR 2,800,201 A1.
However, other mechanisms for generating a current may also exist in such a structure, giving rise to an electric current called dark current, which is not correlated to the absorption of the radiation. The dark current then limits the sensitivity of the detector, since the electric signal supplied by the detector is no longer solely representative of the detected radiation.
Such detectors are used for many applications, ranging from photographic sensors detecting visible rays to imagers operating in the infrared range. In particular, infrared detectors are particularly sensitive to dark currents, which are non-negligible in all cases faced with the currents generated by the radiation.
In order to improve the sensitivity of high-performance infrared detectors, the latter are generally cooled at a low temperature, for example around 80 Kelvin (K) or less.
However, the cryogenic systems used consume considerable energy, and are heavy and bulky, which is problematic for many uses. Furthermore, during the initialization of the detector, reaching the aiming temperature slows the use of the detectors.
Furthermore, the dark current includes generation-recombination and diffusion components with different thermal activation laws. In particular, the dark current related to the generation-recombination phenomena is predominant at low temperatures.